adrial

My car is overall running very poorly, I think its something simple but I need to find the problem.

What's important is that once I get to WOT on boost the car pulls fine. WOT off boost, car exhibits same/worse symptons as part throttle.

When not on boost, I'll give the car some gas and it'll do one of three things:

1) do what its supposed to do, run fine (rare)
2) back fire out the exhaust and intake...and buck and not go anywhere...which must be bad for the car.
3) i'll give it gas and the revs will just drop

In reference to situation #1, it will do this when off boost and part throttle occasionaly for no apparent reason. It will randomly decide to work for 15 seconds and then decide to not go anywhere. The problem is very apparent revving it in neutral.

The car really isn't driveable right now.

Any thoughts/suggestions would be greatly appreciated.

At some points when the car was idling, I could hear the barn door of the AFM slam closed, idle drop a few 100rpm and then pick back up...

I just replaced the AFM with a used unit and the crank/reference sensors (with new ones of course, along with a new mounting bracket).

TIA,
Adrial

Dal Heger

Did you check your throttle position sensor? It should click when the throttle just starts to move.
It's easy and cheap to replace.

Good luck!

Dal.

adrial

Yup, TPS is adjusted fine and was replaced within 5k miles.

MySwiss

I had a similar problem but not as bad.It ended up being a leak at the intake manifold,which caused a erratic idle but a fine wot. You should also look for vacum leaks under the manifold and intake track since those are pretty common. Good luck.

951Tom

I would start with checking the fuel pressure. Then both temp sensors. How is your ignition system...plugs, wires???

Perry 951

Tom said everything I was gonna ask.

adrial

Plugs are fresh as of ~15k miles, cap and rotor replaced 5k miles ago, wires are of unknown age but I tested for arcing 5k miles ago and saw no signs of it. The test for arcing included running the engine in the dark and then misting water over the wires.

I'm gonna throw the rail gauge on it when I go home tomorow night (yeah, 2 hour drive just to try to get the car working).

So far my list of stuff to check tomorow night includes:
Check AFM connections, clean
O2 sensor, try unplugging
check for Vac leaks
check Fuel pressure, adjust if necesary (car has AFPR from Lindsey Racing).
Swap DME relay with the old working unit I yanked 5k miles ago for ****s and giggles.

I've got my fingers crossed...

thanks,
Adrial

dmoffitt

15k is a long time in the sence that the plugs could be plenty fouled one way or another... ?

Danno

Sounds like a bad AFM to me. Tap into the air-flow meter signal at pin#7 on the DME (green/red-stripe wire). Hook up a voltmeter and monitor its readings. It should be about 0.79-0.85v at idle. Then as you accelerate, it should increase voltage smoothly without any sudden fluctuations up & down.

Also check the TPS position signal as well. Tap into KLR line #22 (white/green-stripe). With car ON, but not running, slowly open and close the throttle. You should see a continuous and smooth voltage increase from about 0.25 at closed-throttle to 3.75v at fully open. Shouldn't have any sudden jumps up or down.

BTW, what phase is the moon in at our location when this was happening?

adrial

Danno, those are my thoughts too, but it was just replaced with a working unit from a 65k mile car.

I'll clean up the connections and test it though...THough I think I'll test it right at the AFM instead of at the DME (easier)...unless there's a significant difference??

Silverbullet951

How much is a new TPS? I think I'm having the same problem, the cover for the TPS broke off, (i don't know how), and I'm geting this hesitation as I accelerate, but WOT is fine.

El Schön Toro

Silver,
A new TPS is $55.95 from Paragon.
<a href="http://www.paragon-products.com/" target="_blank">http://www.paragon-products.com/</a>

Good Luck, Guy

adrial

Just thought I'd let you guys know that all is well...

I dont know what I did, I tested both the old AFM and the new one and they both tested out fine...

I reconnected the grounds for my gauges (a/f and boost).

I put the fuel pressure gauge on there...it was at 36, after the car was running good I did a little tuning and brought it up to 40. (vac line connected).

I hit the DME a little...hehe...and wiggled the harness a bit.

Anyway, the car runs great now, dont know what was up.

Thanks for the suggestions.

--adrial

Silverbullet951

</font><blockquote><font size="1" face="Verdana,Tahoma,Helvetica">quote:</font><hr /><font size="2" face="Verdana,Tahoma,Helvetica">Originally posted by Guy Loranger:
<strong>Silver,
A new TPS is $55.95 from Paragon.
<a href="http://www.paragon-products.com/" target="_blank">http://www.paragon-products.com/</a>

Good Luck, Guy</strong></font><hr /></blockquote><font size="2" face="Verdana,Tahoma,Helvetica">Thanks guy.

badcoupe

I'm having similar probs with my car, idles slow and runs terrible off boost but really hauls on boost. more ideas? If I don't use CV anymore than is the banjo bolt and line to the inlet of the turbo from it required anymore? I have the wastegate port plugged off.